Polymer polyol and preformed stabilizer systems

ABSTRACT

A preformed stabilizer composition based on a precursor stabilizer obtainable by reacting a silicon atom containing compound of formula R n  SiX 4-n  or R n  Si((--OSi(R 1 ) 2 ) p  X) 4-n  wherein the R groups are independently saturated or unsaturated hydrocarbyl groups, at least one R group being an olefinically unsaturated hydrocarbyl group; R 1  is a hydrocarbyl group, X is a C 1  to C 10  alkoxy group, n is an integer from 1 to 3 and p is an integer greater than zero, with a polyether polyol having an average molecular weight in excess of 400 and a hydroxyl number in the range 20 to 280 is used to manufacture polymer polyol compositions having a combination of (a) high polymer content, from 30 weight percent to 60 weight percent, (b) lower viscosities, typically less than 9,000 centipose, (c) product stability such that 100% passes through a 150 mesh screen, and (d) up to 100% of the polymer solids content passes through a 700 mesh screen.

The present invention relates to a polymer polyols and a process for thepreparation thereof, and preformed stabilizer used for the preparationof polymer polyols.

Polymer polyols suitable for the preparation of polyurethane foams andelastomers are well known and are widely used on commercial scale.Polyurethane foams made from polymer polyols have a wide variety ofuses. The two major types of polyurethane foams are slabstock andmoulded foam. Polyurethane slabstock foams are used in carpet, furnitureand bedding applications. Moulded polyurethane foams are used in theautomotive industry for variety of applications.

Polymer polyols are produced by polymerizing one or more ethylenicallyunsaturated monomers dissolved or dispersed in a polyol in the presenceof a free radical catalyst to form a stable dispersion of a polymerparticles in the polyol. Initially, polymer polyols producingpolyurethane foams having higher load-bearing properties than thoseproduced from unmodified polyols were prepared using acrylonitrilemonomer; however, many of these polymer polyols had undesirably highviscosity.

Presently, polyurethane foams having high load-bearing properties arepredominantly produced using polymer polyols which are prepared using ahigh styrene content monomer mixture (e.g., 65 to 75 percent styrene).However, polymer polyols produced from such high styrene monomer mixtureoften do not satisfy the ever-increasing industry needs, includingacceptable viscosity, strict stability requirements and increasedload-bearing properties.

Stability and low viscosity of polymer polyols is of increasingimportance to polyurethane foam manufacturers due development ofsophisticated, high speed and large volume equipment and systems forhandling, mixing and reacting polyurethane-forming ingredients. Polymerpolyols must meet certain minimum polymer particles size requirements toavoid filters, pumps and other parts of such foam processing equipmentbecoming plugged or fouled in relatively short periods of time,

Numerous attempts have been made to produce polymer polyols which willmeet foam processing and load-bearing properties required bypolyurethane foam industry.

U.S. Pat. No. 4,242,249 (Van Cleve et al) describes polymer polyolsprepared by using certain preformed dispersants or stabilizers. Thesepolymer polyols provide stability satisfactory for commercialproduction, and use of at least one of (i) high amounts of styrene orother comonomer with acrylonitrile, (ii) higher solids contents or (iii)the use of lower molecular weight polyols. The particular stabilizerused and the concentration used vary with respect to the monomer systemused in the preparation of polymer polyols.

U.S. Pat. No. 4,652,589 (Simroth et al) describes stabilizer precursorsfor polymer polyols. Stabilizer A is made by reacting a 34 hydroxylnumber, 15 weight percent ethylene oxide capped polyoxypropylene triolwith maleic anhydride and subsequently with ethylene oxide. Stabilizer Ahas a hydroxyl number of 32, an unsaturation of 0.1 meq/g, with theunsaturation being 30/70 maleate/fumarate. Stabilizer B is made byreacting a 28 hydroxyl number sorbitol started polyol, containing 10percent internal ethylene oxide, with maleic anhydride, and subsequentlywith propylene oxide. Stabilizer B has a hydroxyl number of 28 and anunsaturation of approximately 0.07 meq/g, with the unsaturation being ofthe fumarate type.

U.S. Pat. No. 5,196,476 (Simroth) describes: (a) a high potencypreformed stabilizer; (b) the use of same in the manufacture of polymerpolyols having high solids content, lower viscosity and excellentproduct stability; and (c) a polyurethane made using such polymerpolyol. The preformed stabilizer is the free radical polymerizationproduct of at least one free radically polimerizable ethylenicallyunsaturated monomer and at least one polyhydric alcohol adductcomprising a polyhydric alcohol residue and a residue of a compoundhaving fumaric or maleic type unsaturation.

U.S. Pat. No. 5,364,906 (Critchfield et al) describes a method forproducing a stable, low viscosity polymer polyol via a modified seedmethod by the steps of (1) producing a first reaction product bypolymerizing a first feed in a first continuous reactor in the presenceof an initiator, the first feed comprising less than 50 weight percentof a total monomer proportion in at least 50 weight percent of a totalbase polyol proportion, optionally in the presence of a precursorstabilizer which is prepared by reacting a polyol with maleic anhydride;and (2) producing a second reaction product by polymerizing a secondfeed in a continuous reactor in the presence of an initiator, the secondfeed comprising (a) the first reaction product, (b) at least 50 weightpercent of the total monomer proportion, and (c) any balance of the basepolyol proportion.

European Patent No. 0 162 589 B1 (Cloetens et al) describes a nonaqueousdispersion stabilizer which is the reaction product of a polyetherpolyol having an average molecular weight greater than 400 and ahydroxyl number in the range of 20 to 280 with silicon atom containingcompound having at least least one olefinically unsaturated functionalgroup and at least one functional group attached to the silicon atomwhich is reactable with the hydroxyl groups on the polyether polyol.

Additional prior art of interest include U.S. Pat. No. Re. 32,733(Simroth et al); U.S. Pat. No. 3,931,092 (Ramlow et al); U.S. Pat. No.4,014,846 (Ramlow et al)); U.S. Pat. No. 4,093,573 (Ramlow et al); U.S.Pat. No. 4,148,840 (Shah); U.S. Pat. No. 4,172,825 (Shook et al); U.S.Pat. No. 4,342,840 (Kozawa et al); U.S. Pat. No. 4,390,645 (Hoffman etal); U.S. Pat. No. 5,394,491 (Hoffman); U.S. Pat. No. 4,454,255 (Ramlowet al); U.S. Pat. No. 4,458,038 (Ramlow et al); and U.S. Pat. No.4,745,153 (Hoffman).

Although there has been progress in reduction of viscosity and increasedin solids content of polymer polyols, there is still a need for polymerpolyols having improved processing and load-bearing properties and foralternate method for making same.

The present invention is directed to a preformed stabilizer compositionand to the manufacture of polymer polyols therewith which polymerpolyols possess a combination of (a) high polymer content, from 30weight percent to 60 weight percent, (b) lower viscosities, typicallyless than 9,000 centipose, (c) product stability such that 100% passesthrough a 150 mesh screen, and (d) up to 100% of the polymer solidscontent passes through a 700 mesh screen.

In one aspect, the present invention concerns a preformed stabilizercomposition for use in the preparation of polymer polyols comprising thereaction product of

(i) a polyol;

(ii) a precursor stabilizer obtainable by reacting a silicon atomcontaining compound of formula

    R.sub.n SiX.sub.4-n or R.sub.n Si((--OSi(R.sup.1).sub.2).sub.p X).sub.4-n

wherein the R groups are independently saturated or unsaturatedhydrocarbyl groups, at least one R group being an olefinicallyunsaturated hydrocarbyl group; R¹ is a hydrocarbyl group, X is a C₁ toC₁₀ alkoxy group, n is an integer from 1 to 3 and p is an integergreater than zero, with a polyether polyol having an average molecularweight in excess of 400 and a hydroxyl number in the range 20 to 280;

(iii) at least one ethylenically unsaturated monomer which iscopolymerizable with the precursor stabilizer; and

(iv) a free radical polymerization initiator.

In another aspect, the present invention concerns a process for thepreparation of the preformed stabilizer composition which processcomprises providing above mentioned composition components (i), (ii),(iii) and (iv) in a reaction zone maintained at a temperature sufficientto initiate a free radical polymerization, and under sufficient pressureto maintain only liquid phases in the reaction zone, for a period oftime sufficient to react essentially all the precursor stabilizer andrecovering a heterogenous mixture containing the preformed stabilizercomposition.

In another aspect, the present invention concerns a polymer polyolcomposition which has a polymer content of 30 to 60 weight percent,based on total weight, a viscosity in centipose of not more than 8,000and product stability such that essentially 100% passes through a 150mesh screen and up to 100% passes through a 700 mesh screen produced bya free radical polymerization of the composition comprising:

(a) a polyol;

(b) the above preformed stabilizer composition;

(c) at least one ethylenically unsaturated monomer;

(d) a free radical polymerization initiator; and, optionally,

(e) a chain transfer agent.

In another aspect, the present invention concerns a process for thepreparation of a polymer polyol composition which process comprisesproviding above mentioned polymer polyol forming composition components(a), (b), (c) and (d) in a reaction zone maintained at a temperaturesufficient to initiate a free radical polymerization, and undersufficient pressure to maintain only liquid phases in the reaction zone,for a period of time sufficient to react a major portion of theethylenically unsaturated monomer to for a heterogenous mixturecontaining the polymer polyol and recovering recovering same from thisheterogenous mixture.

Yet in another aspect, the present invention concerns a polymer polyolcomposition which possesses a polymer content of 30 to 60 weightpercent, based on total weight, a viscosity in centipose of no more than8,000 and product stability such that essentially 100% passes through a150 mesh screen produced by a free radical polymerization of the abovepolymer polyol forming composition.

Yet in another aspect, the present invention concerns a polyurethanefoam forming composition comprising the above polymer polyolcomposition, a polyurethane catalyst, an organic polyisocyanate, asilicone surfactant, and a blowing agent

Yet in another aspect, the present invention concerns a polyurethanefoam made from the above polyurethane foam forming composition.

Precursor stabilizers useful in the present invention are obtained byreacting a silicon atom containing compound of formula

    R.sub.n SiX.sub.4-n or R.sub.n Si((--OSi(R.sup.1).sub.2).sub.p X).sub.4-n

wherein the R groups are independently saturated or unsaturatedhydrocarbyl groups, at least one R group being an olefinicallyunsaturated hydrocarbyl group; R¹ is a hydrocarbyl group, X is a C₁ toC₁₀ alkoxy group, n is an integer from 1 to 3 and p is an integergreater than zero, with a polyether polyol having an average molecularweight in excess of 400 and a hydroxyl number in the range 20 to 280.The particularly preferred precursor stabilizers are the reactionproducts of vinyltrimethoxy silane, vinyltriethoxy silane orvinyltripropoxy silane with a polyetherpolyol having an averagemolecular weight in excess of 400 and a hydroxyl number in the range 20to 280. These precursor stabilizers and their preparation are describedin European Patent No. 0 162 589 B1 (Cloetens et al).

The polyols used in the composition for preparing the preformedstabilizer composition of this invention may be for example polyetherpolyols, polyhydroxyl containing polyesters, polyhydroxyl terminatedpolyurethane polymers, polyhydric polythioethers, andpolytetrahydrofurans. These polyols are well known and are commerciallyavailable. The preferred polyols are the polyether polyols. Thepolyether polyol used should have a number average molecular weight inexcess of 400, preferably from 3,000, more preferably from 5,000 and ahydroxyl number in the range 20 to 280. Most preferably, the polyetherpolyol should be a poly(oxyethylene) (oxypropylene) adduct of an alcoholselected from glycerol, trimethylolpropane, diethylene glycol, theisomers of butanetriol, pentanetriol and hexanetriol andpentaerythritol, sucrose and sorbitol. A mixture of polyols can be used,if desired. The polyol concentration in the preformed stabilizer formingcomposition is not critical and can be varied within wide limits.Typically, the concentration can vary from 50 to 90 weight percent oreven more, preferably 60 to 70 weight percent, based on the total feedto the reactor. A mixture of various useful polyols can be used, ifdesired.

Any ethylenically unsaturated monomer which is free radicallypolymerizable can be used as component (iii) in the preformed stabilizerforming composition of this invention. It is preferred to use vinylmonomers. Styrene, acrylonitrile, methacrylonitrile and methylmethacrylate are preferred vinyl monomers. Most preferred vinyl monomersare styrene, acrylonitrile and mixtures thereof. Typically, a minimum of2 to 20 percent by weight of an ethylenically unsaturated monomer isused in the preformed stabilizer forming composition. When a mixture ofstyrene and acrylonitrile is used, the weight proportion of styrene canvary from 20 to 80 weight percent and acrylonitrile can accordingly varyfrom 80 to 20 weight percent of the mixture. A styrene to acrylonitrileratio in the monomer mixture of from 80:20 to 20:80 is preferred, withthe ratio of from 70:30 to 50:50 being most preferred.

The free radical polymerization initiator useful in the preparation ofthe preformed stabilizer of this invention can be any compounds whichare routinely used to effect grafting of an ethylenically unsaturatedpolymer to a polyol including peroxides, perborates, persulphates,percarbonates and azo compounds. Typical examples of such free radicalinitiators include, alkyl and aryl hydroperoxides, dialkyl and diarylperoxides, dialkylperoxydicarbonates and azobis(nitriles). Preferredfree radical initiators are tert-butylperoxy diethyl acetate andtert-butyl peroctoate. The free radical initiator concentration in thepreformed stabilizer forming composition is not critical and can bevaried within wide limits. Typically, the concentration can vary from0.01 to 2.0 weight percent or even more, preferably 0.05 to 0.2 weightpercent, based on the total feed to the reactor. The particular freeradical initiator concentration selected will usually be an optimumvalue considering all factors, including costs.

Typically, the polyol is used in an amount of from 50 to less 80 weightpercent, the precursor stabilizer in an amount of from 10 to less than50 weight percent, the monomer in an amount of from 5 to 15 weightpercent and the free radical polymerization initiate in an amount offrom 0.01 to 2 weight percent in the preformed stabilizer formingcomposition of this invention.

The process for preparing the preformed stabilizer is similar to theprocess for preparing the polymer polyol. The temperature range is notcritical and may vary from 80° C. to 150° C. The preferred temperaturerange is from 110° C. to 130° C. The mixing conditions used are thoseobtained using a back mixed reactor. The reactors of this type keep thereaction mixture relatively homogenous and so prevent localized highmonomer to precursor stabilizer ratios such as occur in tubularreactors, where all of the monomer is added at the beginning of thereactor.

The present invention also concerns the preparation of stable, highsolids polymer polyols compositions which have acceptable viscosities.

The polymer polyol composition of the present invention possesses apolymer content of from 30, preferably 40, most preferably 40 weightpercent, to 50 weight percent, the remainder being liquid polyol. Overthe range of solids content, it can have a viscosity in centipose lessthan 9,000. The polymer polyol compositions of the present inventionalso show exceptional stability such that essentially 100 percent passesthrough a 150 mesh screen and a significant amounts of high solidscontent polymer polyol, essentially 100 percent passes through 700 meshscreen. As shown in the examples, polymer polyol compositions having asolids content of 42.2, 45.2, 40.6 and 41.8 percent, with a viscosity of5550, 6800, 4950 and 3280 centipose, respectively, all passedessentially 100 percent through a 700 mesh screen.

The polymer polyol composition of the present invention is the reactionproduct of the composition comprising: (a) a polyol; (b) the preformedstabilizer composition of the present invention; (c) at least oneethylenically unsaturated monomer; and (d) a free radical polymerizationinitiator.

The process for preparing the polymer polyols of the present inventioncomprises: (1) providing a heterogenous mixture of the preformedstabilizer composition of the present invention in combination with apolyol, at least one free radically polymerizable monomer and a freeradical polymerization initiator, in a reaction zone maintained at atemperature sufficient to initiate a free radical polymerizationreaction, and under sufficient pressure to maintain only liquid phasesin the reaction zone, for a period of time sufficient to react a highproportion of the at least one ethylenically unsaturated monomer, andrecovering the resulting polymer polyol.

Any known polyol having a functionality of at least two and a molecularweight in excess of 400, preferably from 1,000 and 15,000, morepreferably from 2,00 to 8,000, and a hydroxyl number in the range 20 to280 can be used for the preparation of polymer polyols of the presentinvention. These polyols are well known and are available commercially.The same or different polyol as the one used for the preparation of thepreformed stabilizer may be used for the preparation of the polymerpolyol composition of this invention. Useful polyols may be for examplepolyether polyols, polyhydroxyl containing polyesters, polyhydroxylterminated polyurethane polymers, polyhydric polythioethers, andpolytetrahydrofurans. The preferred polyols are the polyether polyols.Most preferably, the polyether polyol should be a poly (oxyethylene)(oxypropylene) adduct of an alcohol selected from glycerol,trimethylolpropane, diethylene glycol, the isomers of butanetriol,pentanetriol and hexanetriol and pentaerythritol. The polyolconcentration in the polymer polyol forming composition is not criticaland can be varied within wide limits. Typically, the concentration canvary from 40 to 80, preferably 45 to 70, more preferably from 50 to 60,weight percent, based on the total feed to the reactor. The particularpolyol used will depend on the end use of the polyurethane foam to beproduced. A mixture of various useful polyols can be used, if desired.

Any ethylenically unsaturated monomer which is free radicallypolymerizable can be used as component (iii) in the preformed stabilizerforming composition of this invention. It is preferred to use vinylmonomers. Preferred vinyl monomers are styrene, acrylonitrile,methacrylonitrile and methyl methacrylate. The most preferred vinylmonomers are styrene, acrylonitrile and mixtures thereof. Typically, aminimum of 30 to 60 percent by weight of an ethylenically unsaturatedmonomer is used in the preformed stabilizer forming composition. When amixture of styrene and acrylonitrile is used, the weight proportion ofstyrene can vary from 80 to 20 weight percent and acrylonitrile canaccordingly vary from 80 to 20 weight percent of the mixture. A styreneto acrylonitrile ratio in the monomer mixture of from 80:20 to 20:80 ispreferred, with the ratio of from 70:30 to 50:50 being most preferred.

The free radical polymerization initiator useful in the preparation ofthe preformed stabilizer of this invention can be any compounds whichare routinely used to effect vinyl polymerization reaction includingperoxides, perborates, persulphates, percarbonates and azo compounds.Typical examples of such free radical initiators include, alkyl and arylhydroperoxides, dialkyl and diaryl peroxides, dialkylperoxydicarbonatesand azobis(nitriles). Preferred free radical initiators are2,2'-azobis(isobutyronitrile) and 2,2'-azobis(methylbutyronitrile). Thefree radical initiator concentration in the polymer polyol formingcomposition is not critical and can be varied within wide limits.Typically, the concentration can vary from 0.01 to 5.0 weight percent,preferably 0.01 to 2.0 weight percent, more preferably 0.05 to 0.2weight percent, based on the total feed to the reactor. The particularfree radical initiator concentration selected will usually be an optimumvalue considering all factors, including costs.

If desired, any known chain transfer agent can be used in the prepolymerstabilizer forming composition of the present invention. Preferred chaintransfer agents are monohydroxy alcohols because of their ease ofstripping from the final polymer polyol composition. The most preferredchain transfer agent is isopropanol.

The polymer polyol forming composition is provided into the reactor,preferably a continuous, stirred, back-mixed reactor. The internaltemperature of the reactor is controlled within a range of from 80° C.to 150° C, preferably 110° C. to 130° C. The contents of the reactor arewell mixed with the residence time of at least 5 minutes, preferablypreferably from 15 to 45 minutes.

The polymer polyol composition of the present invention is useful in thepreparation of polyurethane foams. Such polyurethane foams have improvedload-bearing and tensile strength properties without impairment of otherphysical properties of the foam.

The polyurethane foams are prepared by reacting the polymer polyolcomposition of the present invention with a polyfunctional organicisocyanate in the presence of a catalyst for the urethane formingreaction, a blowing agent and a foam stabilizer.

Polyfunctional organic isocyanates which can be used for the preparationof the polyurethane foam are well known and are available commercially.Illustrative examples of useful polyfunctional organic isocyanatesinclude the toluene diisocyanates, especially 2,4-and 2,6-toluenediisocyanate (TDI) as well as any desired mixture of these isomers;2,4'- and 4,4'-diphenylmethane diisocyanate (MDI) as well as any desiredmixture of these isomers; oligomers of MDI (polymeric MDI),polymethylene polyphenyl polyisocyanates (commonly referred to as "crudeMDI"); mixtures of TDI and polymeric MDI and mixtures of the thesepolyisocyanates. Prepolymers of the above isocyanate (e.g. withpolyether polyols, glycols or mixtures of these) can also be used in thepresent invention. The preferred isocyanate is 80/20 TDI (a mixture of80 percent 2,4-toluene diisocyanate and 20 percent 2,6-toluenediisocyanate). Polyfunctional isocyanates are used in amounts well knownto skilled persons.

Any of the known blowing agents conventionally used in the production ofpolyurethane foams can be used. Suitable blowing agents include waterand halogenated hydrocarbons of low molecular weight. The blowing agentsare used in amounts well known to skilled persons.

Any of the polyurethane catalysts normally used in the preparation ofpolyurethane foams may be used in the process of the present inventionincluding tertiary amines and organometallic compounds. The polyurethanecatalyst is used in amounts well known to skilled persons. Mixtures ofpolyurethane catalysts may also be employed in the process of thepresent invention.

Any of the foam stabilizers or surfactants for cell stability or othercell size control agents normally used in the preparation ofpolyurethane foams can be used in the present invention. The foamstabilizers, surfactants for cell stability or other cell control agentsare used in amounts well known to skilled persons. Mixtures of one oneor more stabilizers and/or one or more surfactants may also be used.Suitable surfactants include the diverse silicone surfactants,preferably those which are block copolymers of a polysiloxane and apolyoxyalkylene as described in U.S. Pat. No. 3,629,308.

Known crosslinkers may also be used in the process of the invention tomodify polyurethane foam properties. These crosslinkers are used inamounts well known to skilled persons.

In addition to the above mentioned materials, any number of a variety ofadditives conventionally used in the production of polyurethane foamssuch as, for example, fire retardants, defoamers, anti oxidants, moldrelease agents, dyes, pigments and fillers can also be used in theprocess of the present invention. These additives are used in amountswell known to skilled persons.

The following designations, symbols, terms and abbreviations are used inthe Examples below:

CP-3040 is a glycerine started polyol having hydroxyl number in therange of 54 to 59 and Average Molecular Weight of 3,000 and viscosity at25° C. of 490 cps, available from The Dow Chemical Company under thetrademark VORANOL CP-3040.

CP-4702 is a glycerine started polyol having hydroxyl number in therange of 33-38 and Average Molecular Weight of 4,700 and viscosity at25° C. of 820 cps, available from The Dow Chemical Company under thetrademark VORANOL CP-4702.

DNC-635.04 is a sorbitol started polyol having hydroxyl number of 30 andAverage Molecular Weight of 7000.

VTMSP vinyltrimethoxy silane modified precursor stabilizer preparedaccording to Example 3 of EP-0 162 589 B1.

Trigonox 27 is a free radical polymerization initiator sold by AkzoChemie under the trademark TRIGONOX 27.

Vazo 67 is a 2,2'-Azobis(2-methylbutanenitrile) polymerization catalystmade by E. J. duPont de Nemours and Co.

Dabco 33LV a 33 percent solution of triethylene diamine in dipropyleneglycol, sold by Air Products and Chemicals Inc. under the trademarkDABCO 33LV.

Niax A-107 is a formic-acid-blocked version of 70%bis(2-dimethylaminoethyl)ether/30% dipropylene glycol amine catalystavailable from Union Carbide Corp. under the trademark NIAX A-107.

DEOA is Diethanolamine.

DC-5164 is a silicone surfactant sold by Dow Corning Corporation.

IPA is isopropanol.

TDI-80 is a 80:20 mixture of the 2,4- and 2,6-toluene diisocyanateisomers sold by the Dow Chemical Company under the trademark VoranateT80.

Index is the ratio of the amount of reactive isocyanate groups in thereaction mixture divided by the amount of active hydrogen groups in thereaction mixture multiplied by 100.

STN is Styrene.

ACN is Acrylonitrile.

Properties of the polymer polyol composition and polyurethane foamsgiven in the Examples below are determined according to the followingtest methods:

Air Flow (cfm) is measured according to the ISO 7231 test method (onAMSCOR foam porosity instrument).

Density is measured according to the DIN 53420 test method.

CFD 40% (kPa) is Compression Force Deflection determined according toDIN 53577.

IFD 25% (N) is Indentation Force Deflection 25% determined according toASTM D-3574, Test B1 and B2.

IFD 40% (N) is Indentation Force Deflection 40% determined according toASTM D-3574, Test B1 and B2.

IFD 65% (N) is Indentation Force Deflection 65% determined according toASTM D-3574, Test B1 and B2.

SAG factor is Indentation Force Deflection 65% divided by IndentationForce Deflection 25%.

Tensile Strength (kPa) is determined in accordance with ASTM D-3574.

Elongation (%) is determined in accordance with ASTM D-3574, Test E.

Tear Strength (N/m) is determined in accordance with ASTM D-3574.

Filterability is Filtration Hindrance determined by diluting one part byweight sample (e.g. 470 g) of polymer polyol with two parts by weightanhydruous isopropanol (e.g. 960 g) to remove any viscosity-imposedlimitations and using a fixed quantity of material in relation to fixedcros-sectional area of screen, such that all of the polymer polyol andisopropanol solution passes by gravity through a 150-mesh or 700-meshscreen. The 150-mesh screen has a square mesh with average mesh openingof 105 microns and is a "Standard Tyler" 150 square-mesh screen. The700-mesh screen is made with a Dutch twill weave. The actual screen usedhad a nominal opening of 30 microns. The amount of sample which passesthrough the screen within 3000 seconds is reported as percent, a valueof 100 percent indicates that over 99 weight percent passed through thescreen

Viscosity is measured using a Brookfield viscometer, spindle # LVVT3,speed 12, in accordance with ASTM D-4874.

The following examples are given to illustrate the invention and shouldnot be interpreted as limiting it in any way. Unless stated otherwise,all parts and percentages are given by weight.

EXAMPLES 1 AND 2 Preparation of Preformed Stabilizer

The preformed stabilizer was prepared in a continuous polymerizationreactor empolying a tank reactor fitted with baffles and impeller. Thefeed components were pumped into the reactor continuously after goingthrough an in line mixer to assure complete mixing of the feedcomponents before entering the reactor. The contents of the reactor werewell mixed. The internal temperature of the reactor was controlled towithin 1° C. The product flowed out the top of the reactor and into asecond unagitated reactor also controlled within 1° C. The product thenflowed out the top of the second reactor continuously through a backpressure regulator that had been adjusted to maintain at least 65 psigpressure on both reactors. The preformed stabilizer then flowed througha cooler into a collection container. The preformed stabilizer feedcompositions are shown in Table 1 below.

                  TABLE 1                                                         ______________________________________                                        Example              1      2                                                 ______________________________________                                        Formulation:                                                                  CP-4702    parts         45.8   0                                             DNC 635.04 parts         0      81.8                                          VTMSP      parts         46.0   10.0                                          Trigonox 27                                                                              parts         0.2    0.2                                           STY        parts         5.6    5.6                                           ACN        parts         2.4    2.4                                           ______________________________________                                    

EXAMPLES 3 TO 9 Preparation of Polymer Polyol Composition

The polymer polyol of the present invention was prepared using acontinuous polymerization system, using a tank reactor fitted withbaffles and impeller. In Examples 3 to 4 and 6 to 9, the polymer polyolcomposition feed components were pumped into the reactor continuouslyafter going through an in line mixer to assure complete mixing of thefeed components before entering the reactor. The contents of the reactorwere well mixed. The internal temperature of the reactor was controlledto within 1° C. The product flowed out the top of the reactor and into asecond unagitated reactor also controlled within 1° C. The product thenflowed out the top of the second reactor continuously through a backpressure regulator that had been adjusted to give about 45 psig pressureon both reactors. The crude polymer polyol product then flowed through acooler into a collection vessel. Percent by weight polymer in thepolymer polyol was determined from analysis of the amount of unreactedmonomers present in the crude product. The crude product was vacuumstripped to remove volatiles before testing. The polymer polyol inExample 5 was prepared by the same procedure as used in Examples 3 to 4and 6 to 9 except that the preformed stabilizer was continuouslyfed intothe polymer polyol forming reactor from the reactor it was prepared inwhile the rest of the polymer polyol composition feed was pumped intothe same reactor. All the polymer polyols produced were stablecompositions. The polymer polyol feed compositions, preparationconditions and polymer polyol properties are shown in Table 2 below.

                                      TABLE 2                                     __________________________________________________________________________    Example    3   4   5   6   7   8   9                                          __________________________________________________________________________    Formulation:                                                                  CP-4702 parts                                                                            50.6                                                                              48.3                                                                              50.3                                                                              0   44.3                                                                              49.8                                                                              50.6                                       CP-3040 parts                                                                            0   0   0   51.6                                                                              0   0   0                                          Preformed                                                                             parts                                                                            3.8 3.3 3.8 3.8 6.6 4.3 0                                          Stabilizer of Ex. 1                                                           Preformed                                                                             parts                                                                            0   0   0   0   0   0   3.8                                        Stabilizer of Ex. 2                                                           Vazo 67 parts                                                                            0.4 0.4 0.4 0.4 0.4 0.41                                                                              0.41                                       STY     parts                                                                            24.3                                                                              26.0                                                                              24.5                                                                              28.9                                                                              24.2                                                                              24.5                                                                              24.3                                       ACN     parts                                                                            16.2                                                                              17.3                                                                              16.3                                                                              12.4                                                                              19.8                                                                              16.3                                                                              16.2                                       IPA     parts                                                                            4.7 4.7 4.7 2.9 4.7 4.7 4.7                                        Prep. Conditions                                                              React. Temp.                                                                          ° C.                                                                      125 125 125 125 115 115 125                                        Monomer in total                                                                      wt %                                                                             40.5                                                                              43.3                                                                              40.8                                                                              41.3                                                                              44  40.8                                                                              40.5                                       feed                                                                          Ratio ACN/STY                                                                            40/60                                                                             40/60                                                                             40/60                                                                             30/70                                                                             45/55                                                                             40/60                                                                             40/60                                      Residual STY                                                                          parts                                                                            0.22                                                                              0.22                                                                              1.3 1.12                                                                              0.10                                                                              0.3 0.2                                        Residual ACN                                                                          parts                                                                            0.78                                                                              0.76                                                                              1.64                                                                              0.52                                                                              0.30                                                                              0.9 0.8                                        Total polymer                                                                         wt %                                                                             42.2                                                                              45.2                                                                              40.6                                                                              41.8                                                                              45.9                                                                              41.7                                                                              41.4                                       Product                                                                       Properties                                                                    Viscosity                                                                             cps                                                                              5550                                                                              6800                                                                              4950                                                                              3280                                                                              8780                                                                              6180                                                                              5200                                       Filterability:                                                                150-mesh                                                                              %  100 100 100 100 100 100 100                                        700-mesh                                                                              %  100 100 100 100 100 100 100                                        __________________________________________________________________________

EXAMPLES 10 TO 11 Preparation of Polyurethane Foams

Polyurethane foams were produced by pouring foam formulations shown inTable 3 below into an aluminum, 16 liter (40×40×10 cm), 4 vent holesmould heated to a temperature of about 60° C. using Admiral highpressure pouring machine DHF-I and Krauss Maffei MK12-12/16-UL-2K Duplexmixing head and allowing the foam to rise and curing. The foam demouldtime was 5 minutes. Kluber 918/9K mould release agent (sold by KluberAG) was used as the mould release agent. The polyol component/isocyanatecomponent tanks pressure was 3 bars. Both the polyol component andisocyanate components were dispensed at about 150 bars pressure. PolymerPolyol A used in the foam formulation shown in Table 3 below is thepolymer polyol produced in Example 3 herein, diluted with CP-4702 basepolyol. Polymer Polyol A has viscosity (at 25° C.) of 3,000 cps and asolids content of 28 weight percent. Polymer Polyol B used in the foamformulation shown in Table 3 below is the polymer polyol produced inExample 3 herein, diluted with CP-4702 base polyol. Polymer Polyol B hasviscosity (at 25° C.) of 3,400 cps and a solids content of 33 weightpercent. Foam formulations and foam properties are shown in Table 3below. As can be seen from Table 3 below, polyurethane foams prepared inExamples 10 and 11 using a the polymer polyol of the present inventionexhibit high load-bearing characteristics without any significant lossin other physical characteristics.

                  TABLE 3                                                         ______________________________________                                        Example               10     11                                               ______________________________________                                        Polyol Component:                                                             Copolymer Polyol A                                                                            parts     100    0                                            Copolymer Polyol B        0      100                                          water           parts     3.6    3.6                                          DEOA (100%)     parts     1.6    1.6                                          Niax A-107      parts     0.2    0.2                                          Dabco 33LV      parts     0.2    0.2                                          DC-5164         parts     1.1    1.1                                          Isocyanate Component                                                          TDI-80          Index     80     80                                           Foam Properties:                                                              Core Density    kg/m.sup.3                                                                              35.4   34.8                                         C.F.D 40%       kPa       4.11   4.86                                         I.F.D. 25%      N         127    156                                          I.F.D. 40%      N         207    251                                          I.F.D. 65%      N         449    556                                          I.F.D. 65%/I.F.D. 25%     11.61  13.96                                        Tensile Strength                                                                              kPa       181    166                                          Elongation      %         116    99                                           Tear Strength   N/m       328    348                                          ______________________________________                                    

I claim:
 1. A polymer polyol composition which has a polymer content of30 to 60 weight percent, based on total weight, a viscosity incentipoise of not more than 9,000 and product stability such thatessentially 100% passes through a 150 mesh screen and essentially 100%passes through a 700 mesh screen produced by a free radicalpolymerization of the composition comprising:(a) a polyol; (b) apreformed stabilizer comprising the reaction product of (i) a polyol;(ii) a precursor stabilizer obtainable by reacting a silicon atomcontaining compound of formula R_(n) SiX_(4-n) or R_(n)Si((--OSi(R¹)₂)_(p) X)_(4-n) wherein the R groups are independentlysaturated or unsaturated hydrocarbyl groups, at least one R group beingan olefinically unsaturated hydrocarbyl group; R¹ is a hydrocarbylgroup, X is a C₁ to C₁₀ alkoxy group, n is an integer from 1 to 3 and pis an integer greater than zero, with a polyether polyol having anaverage molecular weight in excess of 400 and a hydroxyl number in therange 20 to 280; (iii) at least one ethylenically unsaturated monomerwhich is copolymerizable with the precursor stabilizer; and (iv) a freeradical polymerization initiator; (c) at least one ethylenicallyunsaturated monomer; (d) a free radical polymerization initiator; and,optionally, (e) a chain transfer agent.
 2. The polymer polyolcomposition as claimed in claim 1 wherein the at least one ethylenicallyunsaturated monomer in (b)(iii) or (c) is a mixture of acrylonitrile andstyrene.
 3. A polymer polyol composition as claimed in claim 2, whereinacrylonitrile and styrene are present in the mixture in the ratio offrom 20:80 to 80:20.
 4. A process for the preparation of polymer polyolcomposition which process comprises providing a compositioncomprising:(a) a polyol; (b) a preformed stabilizer comprising thereaction product of (i) a polyol; (ii) a precursor stabilizer obtainableby reacting a silicon atom containing compound of formula R_(n)SiX_(4-n) or R_(n) Si((--OSi(R¹)₂)_(p) X)_(4-n) wherein the R groups areindependently saturated or unsaturated hydrocarbyl groups, at least oneR group being an olefinically unsaturated hydrocarbyl group; R¹ is ahydrocarbyl group, X is a C₁ to C₁₀ alkoxy group, n is an integer from 1to 3 and p is an integer greater than zero, with a polyether polyolhaving an average molecular weight in excess of 400 and a hydroxylnumber in the range 20 to 280; (iii) at least one ethylenicallyunsaturated monomer which is copolymerizable with the precursorstabilizer; and (iv) a free radical polymerization initiator; (c) atleast one ethylenically unsaturated monomer; (d) a free radicalpolymerization initiator; and, optionally, (e) a chain transfer agentina reaction zone maintained at a temperature sufficient to initiate afree radical polymerization, and under sufficient pressure to maintainonly liquid phases in the reaction zone, for a period of time sufficientto react essentially at least major portion of the at least oneethylenically unsaturated monomer and recovering the polymer polyol. 5.A process according to claim 4, wherein the reaction zone is maintainedat the temperature of from 80° C. to 150° C.
 6. A composition for thepreparation of a polyurethane foam comprising a polymer polyol, apolyurethane catalyst, an organic polyisocyanate, a surfactant, and ablowing agent, characterized in that the polymer polyol comprisespolymer polyol as claimed in claim
 1. 7. A polyurethane foam preparedfrom a composition as claimed in claim
 6. 8. A polyurethane foamprepared from a polymer polyol composition as claimed in claim 1.